Average revenue per user (ARPU) is a metric used in the telecom industry to identify trends, with lower ARPU indicating opportunities for growth. The document lists the top 10 countries in 2020 with the lowest ARPU, ranging from $0.69 in Venezuela to $2.09 in Togo, Tanzania, and Zambia. Low ARPU countries present opportunities for telecom businesses to expand services and drive more revenue through innovation.